Eastern Iowa has tons of older smokestack cities/towns that have been deindustralized. As the union members there pass, eastern Iowa may grow more conservative. Plus the ‘Rats have done nothing for them for decades.
Those towns with a large enough college infrastructure and liberal - if not leftist - NGOs (such as Catholic Charities) have had their wells poisoned for the foreseeable future. They won't even vote the sleazier libs on their city councils out, and only "progressive" corporations need apply.